It seems like $parser->getOption() targeting Redaxscript\Console\Parser::getOption() can also be of type null or string; however, Redaxscript\Console\Command\Backup::_database() does only seem to accept array, maybe add an additional type check?

This check looks at variables that are passed out again to other methods.

If the outgoing method call has stricter type requirements than the method itself, an issue is raised.